Refrigeration



A. A. KUCHER Oct. 3l, 1939.

REFRIGERATION Filed March 16, 1932 6 Sheets-Sheet 1 A. A. Kucl-IER Oct.3l, 1939.

REFRIGERATION Filed March 16, 1932 6 SheetS-Sheet 2 HHH Oct. 31, 1939.A, A KUCHER 2,178,020

REFRIGERATION Filed March 16, 1932 6 Sheets-Sheet 3 A. KUCHERREFRIGERATION Oct. 31, 1939.

Filed March 16I l1932 6 Sheets-Sheet 4 9mm. .3P Sh. Q

\\wh.n m

Oct. 31, 1939. A. A. KUCHER REFnIGEnATmN' Filed March 16, 1932 6Sheets-Sheet 5 Oct. 3l, 1939. A, A KUCHER 2,178,020

REFRIGERATION Filed March 16, 193'2v e sheets-sheet e Patented Oct. 31,1939 kUNITED STATES y 2,178,020 REFRIGERATION Andrew A. Kucher, Dayton,Ohio, assg'nor, by mesne assignments, to General Motors Corporation, acorporation of Delaware Application March 16,

10 Claims.

This'invention relates to refrigeration.

It is among the objects of this invention to provide an improved methodof, and apparatus for, mechanical refrigeration of household or 5commercial food preserving cabinets and other objects to be cooled, bywhich method a substantially uniform cabinet temperature is maintainedin a varying environmental or room temperature by a greatly simplifiedautomatic' temperature control and by a refrigerant liquefying unit ofmaterially reduced size and cost.

Heretofore it has been customary to provide household. and otherrefrigerator cabinets with mechanical refrigerating systems havingautomatic controls for maintaining desired temperatures in the cabinet.Usually the controls involve an intermittent operation of therefrigerant liquefying unit, and are generally constructed with the viewthat the best type of control for a modern electric motor, which drivesthe liquefying unit,is the type which intermittently stops themotor,.and causes, alternately, periods of idleness and periods ofoperation at full speed.

While such a type of control permits the use of a modern constant speedelectric motor for driving the liquefying unit, it also necessitates aliquefying unit of excessive size and cost, capable of compensating fortheA loss of heat dissipating powerl in the liquefying unit duringperiods of idleness, and it also requires control mechanism which isrelatively complicated in character and costly to manufacture.

According to this invention, on .the other hand,

I use a constant speed continuously running d liquefying unit driven byan electric motor as a factor in reducing the size and cost of thesystem. The temperature' control of the cabinet is effected by causingthe liquefying unit to ybe operated continuously at a constant speed,and by coordinating the remainder of the refrigerating system with theliquefying unit and with the cabinet in such a manner that a practicallyconstant, or food preserving temperature is maintained in the cabinetregardless of changes in the surrounding or room temperature. Inapplying my invention to a household or similar` cabif net, the cabinetand therefrigerating capacity of the system are properly coordinated insuch av manner that the system removes heat from the cabinet anddissipates it continuously into the surrounding air or other mediumsubstantially as fast and in the same quantity as the heat leaks intothe cabinet from the surrounding atmosphere. In the preferredembodiment, a yclosed cycle, compressor-ondenser-evaporator 1932,Seria.l No. 599,239

`refrigerating system is provided in which the compressor, driven bya'constant speed motor, compresses and evaporates refrigerantcontinuously; and thus removes heat continuously from the evaporatorwhich is cooling the cabinet. The 5 capacity of the evaporator to absorbheat from the interior of the cabinet is modied in proportion with theheat leakage into the cabinet to compensate for changes in the roomtemperature. Accordingly, the evaporator is made of sucient area to coolthe cabinet during the highest room temperatures likely to beencolintered and a refrigerant expanding control is interposed betweenthe evaporator and the condenser capable of varying the quantity ofrefrigerant supplied to the evaporator, andI thereby varyingv theeffective refrigerating area of the evaporator `and its refrigeranttemperature so that the evaporator absorbs heat from the cabinetsubstantially as fast and at the same rate, as the heat leaks into thecabinet.

Wherethe condenser of the system is cooled by the air surrounding thecabinet, or where it is cooled vby some other medium and the condenserpressure still remains a function of the room temperature, I use thecondenser pressure as one of several methods of modifying the heatabsorbing capacity of the evaporator. To

` this end, I interpose a refrigerant expander or restricter between thecondenser and the evaporator, which is responsive,l in part, tocondenser pressure and controls the entrance of refrigerant into theevaporator in such a manner that the quantity of refrigerant, theeffective refrigerating area, and the refrigerant pressure, and'therefore temperature, of thel evaporator are correctly proportioned atall times under varying room temperatures to maintain the cabinettemperature substantially constant, or within proper foodpreservingtemperature limits.

I contemplate many other forms of my inventinembodying one or more ofits phases and coming within the scope of the invention; but for aclearer understanding of the principles I describe hereafter, in moredetail, the application of its principles to the form which utilizes,`in part, the condenser pressure or ternperature as thefactor forcompensating for the varying refrigeration requirements of the cabi-lnet. i

Further objects 'and advantages of the present invention will beapparent from the following description, reference being had to theaccompanying drawings, wherein a preferred form 0 f the presentinvention is clearly shown.

. my invention;

Fig. 5 is another vertical cross-sectional view taken along the line 5-5of Fig. 4;

Fig. 6 is a topplan view of the evaporator shown in Fig. 4;

Fig. 7 is a cross-sectional View similar to Fig. 5, of a slightlymodified form of evaporator;

Fig. 8 is a cross-sectional view of one form of refrigerant expandingdevice which may be used in connection with my invention; and

Figs. 9 to 11 show charts used in further explanation of my invention.

In applying the principles of this invention to the condenser pressurecontrol form, the heat leakage into a cabinet is coordinated with therefrigerating capacity of a closed cycle,compressor-condenser-evaporator refrigerating. system. The compressor isdriven continuously at a constant speed by a constant speed electricmotor. The condenser is cooled by air having temperature variationscorresponding to those of the air surrounding the cabinet, andpreferably the condenser is mounted on the cabinet in a position to becooled by the air surrounding the cabinet. The evaporator is placed inthermal exchange relation with the interior of the cabinet, such as byplacing it inside the cabinet.

The cabinet and the refrigerating system are coordinated by thefollowing steps which will be more fully described after the followingbrief enumeration:

1. 'I'he heat leak from the surrounding atmosphere into the cabinet isdetermined and reduced to a working coeiiicient, conveniently, in termsof B. t. u.s per hour per degree 'of temperature difference between thesurrounding atmosphere andthe interior of the cabinet.

2. The capacity required of the refrigerating system to maintain thecabinet at a predetermined temperature in an average room temperature iscomputed from the value found under heading 1, also conveniently interms of B. t. u.s per hour.

3. The requirements, in B. t. u.s of refrigeration by the cabinet tomaintain a constant cabinet temperature at various representative roomtemperatures is determined from the value obtained in 1.

4. A complete continuously running refriger-` ating system is designedand constructed to produce the capacity found to be required underheading 2.

v5. A-series of calorimeter tests are performed on the system todetermine its head pressure, back pressure and refrigeration capacitycharacteristics under various room temperatures.

6. Charts are drawn from the data obtained above, which indicate theevaporator and condenser pressures required to be maintained by thesystem at various room temperatures in order to maintain a constantcabinet temperature.

7. A suitable refrigerant expanding' device or restricter, to be placedbetween the condenserI and evaporator, is designed to maintain thecondenser and the evaporator pressures indicated to be necessary bypoints on the charts made in accordance with heading 6.

The above procedure is now more fully described (1) THE DETERMINATION orTHE HEAT LEAK Enom THE SUanoUNnrNo ATMOSPHERE rNTo THE CABINET Anysuitable method of determining this factor may be used. According to onemethod, the cabinet is placed in a relatively low temperature room, suchas one at 50 F. Heat is applied to the inside of the cabinet in knownquantity, for example, by an electrical heater of known currentconsumption. Electrical units consumed by the heater are converted intoheat units, such as B. t. u.s per hour. The temperature diierencebetween the inside of the cabinet and the outside room temperature ismeasured. The total number of B. t. u.s per hour expended in theelectric heater is divided by the number of degrees differential betweenthe inside and the outside of the cabinet, and the result is taken as aconstant coefficient representing the number of B. t. u.s heat leakageper degree difference between room and cabinet temperature, per hour.Within the normal room temperature range likely to be encountered by theapparatus, it can be assumed that the result thus obtained holds truefor any temperautre differential likely to be encountered, although itis to be understood'that under more rigorous 4requirements than thoseprevailing in the usual household refrigerator cabinet, a more accuratedetermination of the heat leak into the cabinet may be made.

For the purpose of a concrete illustration, it is assumed that, in arepresentative cabinet, 3.4 B. t. u.s per degree, per hour ofrefrigeration are required to maintain the cabinet interior one degreecolder than the exterior, this example being an actual value obtained inone ofthe many experiments which I have performed, this particularcabinet having an internal displacement of approximately 5 cu. ft.

(2) CoMPUTATIoN oF CAPACITY REQUmEn oF THE REERIoEaATIoN SYSTEM ToMAINTAIN THE CABINET AT PBEDETEEMINED TEMPERATURE AT AN AVERAGE RoonTEMPERATURE amount of refrigeration required'to maintain the f cabinetat the temperature selected (36 F.) in average room temperature is theproduct of the temperature diierential (-36 F.) Abetween the inside andthe outside of the cabinet times the unit heat leak\ per degree per hourobtained under heading 1 (3.4 B. t. u.). From the values above selected,the computation (ao- 36) X3.4=149.6

indicates that refrigeration equivalent to 149.6 B. t. u.s perl hour isnecessary to maintain an internal box temperature of 36 F. with a roomtemperature of 80 F. `This value of 149.6 B. t. u. per hour is made thebasis of further design and construction of the refrigeration system.

(3) CoMPU'rArIoN or THE CABINET RErRIeEnA'rIoN REQUIREMENTS Fon VABIoUsRooM TEMPERATURES The requirements of any particular cabinet in order tomaintain a substantially constant cabinet interior 'temperature undervarying room temperatures are computed from data obtained underheading 1. Since the B. t. u. requirements per degree of interior andexterior temperature differences pez` hour of any particular cabinet canbe determined in accordance with the teaching of heading 1, the valuethus obtained (3.4 B t. u.s per hour) is multiplied by the totaltemperature differential between -the constant cabinet temperature andeach ofthe varying room temperatures 60, 70,- 80, 90, 100 and 110. Atable to show the proper computation is constructed a as follows:

c= e= a b (a-b) d (cXd) Room Cabinet Temp. Unit v Total temp. temp.dierenheat leak cabinet tial heat leak The above table shows that theparticular cabito be maintained with no substantial deviation.

net being investigated requires 81.6 B. t. u.s per hour of refrigerationin order to maintain an internaltemperature of 36 F.'at a 60 roomtemperature. Likewise it indicates that 115.6 B.- t. u., 149.6 B. t. u.,183.6 B. t. u., 217.6 B. t. u. and

v251.6 B. t. u., of refrigeration are required to maintain this cabinettemperature at room teinperatures, respectively, of 70` F., 80 F., 90F..

However, it. is to be understood that in the usual householdrefrigerator, the box temperature can vary or deviate somewhat from anyparticular temperature so long as the temperature does not drop muchbelow 32 F. or rise much above 50F. for any extended period of time.Therefore, in the design of a refrigeration system, the requirements forhousehold refrigeration do not make it necessary for the box temperatureto be maintained without the slightest deviation from the valueselected. j

Accordingly it is within the contemplation of this invention that thevalues under columns b "Cabinet temperature", c Temperature differentialand e Total cabinet heat leak may be expressed inA terms of upper andlower limits rather than xed temperatures, and that, in the 'plotting oflines C and D hereinafter described, bands instead of lines are formedon the charts, these bands indicating zones of permissible operationrather than inflexible lines from which no deviation can be made.However, this invention can be, and preferably is, practiced withsuchrefinement that box temperatures can be maintained within much narrowertemperature limits than above indicated.

(4) THE DESIGN oF A REFRIGERATING SYSTEM To PRODUCE THE REQUIRED AVERAGECAPACITY WHILE RUNNING CoNTINUoUsLY y A refrigerating system is designedto produce the amount of refrigeration found to be necessaryunderheading 2 which, for the particular values aumed, was' found to be149.6 B. t. u.s o1' refrigeration per hour under a room temperature of80 F. while running continuously at a constant speed. It is deemedunnecessary, under the present development cf the refrigeration art, todescribe fully the necessary steps and computations to design such asystem. As well known, it is necessary to provide a compressor of propervolumetric capacity when used in v`,combination with a selectedrefrigerant; condenser and evaporator. Any. refrigeration engineer, using known methods and ,values can readily'determine the requirements.

(5) CALORIMETER Tas'rs oN THE SYSTEM A series of calorimeter tests arethen performed on the system, in order to determine the refrigeration fcapacity at various evaporator pressures and corresponding condenserpressures in variweighing the amount 'of refrigerant'introduced andremoved from the receptacle I4. A by-pass line I6 is provided, so thatthe system may be operated without disturbing the receptacle I4 or itssetting. For this purpose, valves I-'|, I8 and I9 are provided. 'I'hedischarge from the ref ceptacle I4, or from the by-pass I6, enters anautomatic expansion valve.20 which in turn discharges to an evaporator2| which in turn is connected with an intake of the compressor I0through the medium of an evaporated refrig erant, line 22. The automaticexpansion valve is of the type which automatically maintains a constantpressure within the evaporator and is provided with a suitable manualadjustment, so that it may be set to maintain any desired constantevaporator pressure. Valves of this type are well-known in the art andit is therefore deemed unnecessary to describe them further. Theevaporator 2| is provided with any suitable means for applying heatthereto, such 'as a surrounding water tank 23 ingood thermal contactwith the evaporator 2|. 'Ihe compressor and condenser are placed in aposition with respect to the cabinet 24 substantially identical with thepositions which they are to occupy in the finished product. pansionvalve of the calorimeter system is displaced, in the finished product,by a different refrigerant expander and evaporator, this in no wayaltering the results obtained from the tests..

tion is reached in the system. When this stable condition has-beenreached, the valve I8 is ma- -4 nipulated so that a quantity ofliquidfrefrigerant is introduced into the receptacle I4.

The scales are balanced, and then a balancing weight of arbitrary valueis removed from the The heat absorbing element and exscales pan 15a. Thevalve i1 is then closed and valves i8 and I9 opened with a simultaneoustime reading. The system is operated until it withdraws refrigerant fromthe receptacle I4 until the scales are again balanced, thus indicatingthat a weight of refrigerant has been used equal to that ofthe weightremoved from the scales. A second time reading when the scales are sobalanced permits a determination of the length of time during which thesystem was consuming the known weight of refrigerant from the receptacleI4. A refrigerant whose physical constants are well known is used in thesystem and thus with the readings above indicated, showing a knownweight of refrigerant evaporated in a known period of time, the numberof B. t. u.s of refrigeration per unit of time produced by the system iscalculated. Careful tests are made'at various evaporator or backpressures, so that the charts hereinafter to be described can beproperly plotted. During the calorimeter tests the head, or condenserpressure is read or recorded. The head and back pressure can be read, orrecorded for example, by means of the recording gauges 25 and 26. Withone of the systems which I have tested, calorimeter tests were performedat various back pressures between 5 inches and 25 inches, mercurycolumn, at each of the 'following room temperatures: 60 F., 70 F., 80F., 90 F., 100 F. and 110 F.

(6) THE` PLo'rTINc oF Tnt: CHARTS Chart A With the system on calorimetertest, at a back pressure of 20 inches,` and at a room temperature of 80F. the'system testedby me, using C2ClzF4 as a refrigerant, wasl found toproduce substantially 110 B. t. u.s per hour. This determined one pointon the 80 F. line to be plotted on Chart `A, the point being. indicatedat 30. With the room temperature still at 80 F. and with a back pressurechanged to 15 inches vacuum, the system produced substantially 180 B. t.u.s per hour and thus another point, indicated at 3l, of the 80 F. roomtemperature line of Chart A was determined. With 10 inches vacuum backpressure and still with 80 F. room temperature the system produced 252B. t. u.s per hour and thus point 32 of the 80 F, room temperature linewas determined. With 5 inches vacuum back pressure, with 80 F. roomtemperature the system produced 325 B. t. u.s per hour and thus point 33of the 80" F. -room temperature line was established. The linescorrespondingto 60 F., 70 F.,'90 F., 100 F. and 110 F. were similarlyestablished, the system being operated at each of these roomtemperatures withlback pressures of 5, 10, and 20 inches.

Chart B The data.y taken during the testswhich have *y values forrpointof Chart AY also gave a condenser pressure of. 25 lbs. Thus the point 40is established on Chart B which forms a part of the 80 F. roomtemperature line of this chart. Similarly the data which establishedpoints 3|, 32

and 33 on Chart A also gave condenser pressures.

respectively of 26.5, 28 and. 29 which established respectively points4|, 42 and 43 of the 80 F. room temperature line of Chart B. Similarcondenser pressure readings at the F., '70 F., 90 F., 100 F. and 110 F.room temperatures furnished the data for establishing the other roomtemperature lines of Chart B in the same manner as for Chart A. Forproperly designing a system so that it is capable of producing theresuits of this invention, the head and back pressures which produce aconstant box temperature under heading 3, '70 F. room temperatureindicates that 115.6 B. t. u.s are required by the cabinet and thus theintersection of the F. line with the vertical line from the 115.6 B. t.u. point establishes the point 5i of the line C. Similarly thecomputation under heading 3 indicates that the cabinet requires 149.6;183.6; 217.6 and 251.6 B, t. u.s at F., 90 F., 100 F. and 110 F. roomtemperatures respectively, and thus the intersections of the 80 F., 90F., 100 F. and

110 F. lines with the vei'ticals from these B. t. u.

values respectively establish the points 52, 53. 54 and 55 of the lineC. The line C therefore can be used to indicate the various backpressures necessary in the evaporator in order to'maintain a constantbox temperature of 36 F. at any varying room temperature between 60 F.and 110 F. by laterally projecting to the evaporator pressure scale theintersections of the line C with each of the room temperatures desired.

The plotting of the line D on Chart B establishes the condenserpressures required under varying room temperatures to establish constantbox temperature. The plotting of line D is based on the fact that theconstruction of the Charts A and B indicates corresponding head and backpressures where a horizontal line intersects corresponding roomtemperature lines on these two charts. A horizontal line drawn frompoint 50 on the 60 line of Chart A until it intersects the 60 F. line onChart B establishes'a point 56 on the 60 F. line of Chart B, which, whenprojected vertically downward shows the head pressure which is to bemaintained in the system at that particular room temperature to producethe required B. t. u.s in order to maintain the box at the constanttemperature selected. Similarly a horizontal line drawn from the point5I on the line 70 F. of Chart A until it intersects the '10 F. line ofChart B establishes point 51 of the line D. In the same mannerintersections of horizon# tal lines from the points 53, 54 and 55respectively with the- F., 100 F. and 110 F. lines of Chart B establishthe points 58, 59 and 60 of line D which, when projected verticallydownward establish the respective head pressures required to maintainthe cabinet temperature constant.

The back and head pressure projections from lines C and D as aboveindicated show the pressures which must be maintained in the evapora- .f

tor and the condenser in order to maintain av constant boxtemperature of36 F. in room tem lan peratures varying from F. to 110 F.

(7) THE CONSTRUCTION '0F A REFRIGEBANTEXPANDER CAPABLE 0E MAINTAININGTHE REQUIRED HEAD AND BACK PaEssUREs 'ro MAINTAIN A CONSTANT BoxTEMPERATURE UNDER VARUNG ROOM TEMPERA- TUREs Charts A and B haveestablished a series of head and back pressures which must be maintainedin the refrigerating system in order to maintain a constant cabinettemperature at various room temperatures. An expander is therefore madewhich is capable of maintaining the head and back pressures indicated tobe necessary by Charts A and B, which, with this particular system andcabinet, are as follows:v In a 60 F. room, the head pressure should be15 lbs. as indicated vby projecting point 56 on the 60 F. linevertically downward to the head pressure scale, and the back pressureshould be 23 inches as indicated by projecting point 50 on the 60' F.line horizontally to the evaporator or back pressure scale. In a 110 F.room, the head pressure should be 52.5 lbs. as similarly indicated bypoint 6D, and the back pressure should be 7 inches as similarlyindicated by point 55A. When the expander is constructed to'maintain ahead pressure of 15 lbs. and a back pressure of 223 inches in a 60 F.room, and a head -pressure of 56.5 lbs. against a back pressure ofinches in a 110 F. room, then it automatically maintains substantiallythe proper head and back pressures forV intermediate room temperatureconditions indicated to be required by the charts. Therefore a conditionis established in which the cabinet temperature is maintainedsubstantially at 36 F. throughout the range of room temperatures between60 F. and 110 F.

Various types of restricters are contemplated for use between thecondenser and the evaporator which are capable of maintaining thecondenser and evaporator pressures herein indicated to be required, andin fact, many expanders now in use, when properly designed andcoordinated -in accordance with my invention, are adaptable for use forthis purpose. A properly designed elongated orifice having the properlength and crosssectional area, gives excellent results. Preferably theorifice is of triangular cross-section and is designed with suchcross-sectional area and length that it maintains the proper head andback pressures in the system to produce a constant cabinet temperatureunder varying room temperatures. While elongated orices have beenpreviously used to expand refrigerant between the condenser andevaporator, such orifices havek vbeen utterly lacking in characteristicscapable f maintaining a constant cabinet temperature in varying roomtemperatures in combination with a constant speed constantly runningcompressor. One method of constructing a proper elongated orifice is toplace an orifice of any arbitrary length, cross-sectional area andcontour in the refrigerating system, all of the parts being in theirnormal operating position on the cabinet, and then to calibrate theorifice by varying its length and cross-sectional area under variousconditions of operation until the calibration produces an orifice ofproper length and area' to produce the pressure characteristics whichhave been previously established: f

The calibration of the elongated orifice, hereafter referred to asrestricter, may be performed In either case, after the calibration hasbeen completed, a restricter of definite length 'and cross-sectionalarea has been established which can be duplicated for quantityproduction in this finished form.

For the purpose of this invention it is not necessary to give a highlytechnical description of the laws of flow of an expanding refrigerantthrough an elongated orifice. On the contrary, only such principlesrelating to this subject are here described which are necessary to aid aperson skilled in the art to properly calibrate an elongated orice toobtain the results required.

With these requirements in view, the following general principles andprocedure may be used for calibration of the restricter: Duringcalibration, lengthening the restricter or reducing its cross-sectionalarea has the effect of lowering the back pressure, and/or decreasing thecondenser pressure, whereas'reducing the length or increasing the areaof the restricter has a tendency to increase the evaporator or backpressure and/or raise the condenser pressure.

In View of this inherent characteristic, a restricter of a practicalinitial Alength and crosssectional area is connected in the particularrefrigerating system being developed. Calibration begins by changing itslength or area o1 both, in any constant room temperature (such as theminimum room temperature likely to be encountered) until it maintainsthe desired cabinet temperature by maintaining the head and backpressures indicated, in Charts A and B, to be necessary at this roomtemperature. This calibration, however, is quite likely to beinsufiicient to enable the restricter to maintain the same cabinettemperature in the maximum room temperature likely to be encountered,since entirely different head and back pressures are required under thiscondition. Further calibration is therefore conducted at this high roomtemperature, and thereafter at alternate low and high roomY temmsctures.Each calibration brings the restricter nearer final form, until thedesired result is obtained.

It is necessary i' lr the restricter to maintain proper head and 'tackpressures, and it may be expedient attimes to calibrate the restricterby takinginto account its effect on both head and back pressures.However, under ordinary conditions, calibration can be simplied byusing, as a. guide for calibration, only the effect of the orice on theback pressure of the system, permitting the head pressures to adjustthemselves automatically to their proper values.

Fig. 9 shows a diagram similar to Chart A of Fig. 1 on which have beenplaced certain guides for calibration, using the back pressure of theref frigerating system as the determining factor. In this figure, allpoints on the area to the left of the line C designate pressureconditions producing warmer cabinet temperatures than those desired. Allof the points on the right of the line C designate colder cabinettemperatures. In reading apoint on this chart it must be read withreference not only to the back pressuresV but also with reference toroom temperature. Thus the points m and n, being on the same horizontalline indicate identical back pressure conditions (10 inches) in thesystem; but when these same points are read with reference to the roomtemperature lines, the point m indicates that a back pressure of 10inches in a 110 F. room temperature produces a warmer cabinettemperature than is desired, whereas the same'back pressure of l0 inchesin a 60 F. room temperature produces a colder temperature than isdesired.

The Calibrating rule, as indicated on Fig. 9, is that when a point fallson the left of line C' the cross-sectional area of the restricter isincreased, and that when it falls on the right of line C', therestricter length is increased.

With these rules of calibration in mind, a restricter of practicallength and cross-sectional area, arbitrarily selected, is placed in thesystem' and cabinet and is operated in the coldest room temperature (60F.) likely to be encountered. The result obtained, in terms of backpressure and room temperature is quite likely to be diirerent from thecorrect requirements of point 50. Instead, the result obtained willoccur on the 60F. room temperature line either on the right or left ofline C'. For the purpose of a concrete illustration, it is assumed thatsuch a point will fall at the left and can be designated as the point V.In accordance with the Calibrating rule, the cross-sectional area of theorice is increased until the intersection of back pressure roomtcmperature ordinates occur at point 50'. However, if the proportions ofthe restricter are such that an excessive amount of refrigeration occurswithin the restricter itself, then ra restricter of less initial lengthand cross-sectional area should be used as a starting point incalibration.

The initial calibration, described above, satisiies the requirements atthe 60 F. room temperature, but is probably not suiilcient to provide/anoriiice capable of maintaining the required back pressure in the 110 F.room. Therefore a second step in calibration is performed in the 110 F.room. The result obtained probably will not coincide with the conditionsindicated by the point 55', but may occur at a point either to the rightor to the left of point 55 on the 110 F. room temperature line. For thepurpose of a concrete illustration, it is assumed that the result can beplotted as the point a: on the left of the point 55 along the 110 F.line. The rule for calibration under this condition is to increase thecross-sectional area until it produces back pressure room temperatureconditions substantially the same as those indicated by the point 55.This completes the second step in calibration as indicated in Fig. 9 bythe line |02, the point s: and the arrow pointing to 55.

This second step in calibration has distorted the first 60 F. roomcalibration. -Therefore a third step in calibration is taken. The systemis again operated in the 60 F. room and the result observed. The backpressure produced will, under these conditions probably fall to theright .of line C', and' the result can be indicated by the The rule forcalibration for resultsl point V'. falling to the right of line C isthat the restricter length should be increased. Therefore the length ofthe orifice is increased until the back pressure room temperatureconditions are again substantially equal to the point 50'. Thiscompletes the third step in calibration and has been indicated by line|03, point V' and the arrow pointing to 50'.

A fourth step in calibration is performed in the '110 F. room ifnecessary. The result obtained is plotted on the 110 F. room temperatureline and will lie between the point :c and the point 55. Thus it 'may beindicated by the point 3;', and following the rule of calibration, thecross-sectional area is increased until the back pressure, roomtemperature conditions of point 55' are obtained. This fourth step incalibration is indicated by the line |04, point x' and the arrowpointing to 55.

alternate calibration at high and low room temperatures produces aresult nearer in accord with the line C. Thus, if necessary, furthersteps in calibration may be taken. For instance, a iiith step incalibration includes a chang'efrom the 110 F. room temperature to the 60F. temperature in which the back pressure obtained in the 60 F. roomtemperature is represented by the point V intermediate between V and 50.Since point V" falls on the right of line C', the length of therestricter is increased until the back pressure, roomtemperaturerequirements of point 50 are reestablished. This procedure isindicated by line |05, point V" and the arrow pointing to 50. It will be'observed that the line |05 very nearly coincides with line C', and thatcalibration can be continued until results substantially identical withline C are obtained.

THE DRAWINGS The method of refrigeration herein disclosed is applicableto many types of refrigerating apparatus. For a clearer understanding ofthe invention, and not with the intention of limiting its scope, itsapplication to one particular form, shown in the drawings, is nowdescribed. The refrigerating apparatus includes a cabinet `50 providedwith the usual food preserving space 50a. A compresser 0, a condenserand an evaporator 5| are mounted on, or unitarily assembled with thecabinet. The compressor discharges refrigerant through the pipe 52 tothe condenser where the refrigerant is condensed and is discharged intoa receiver 53 which has now been substituted for the receiver I2 used inthe calorimeter tests. The condensed refrigerant then passes through thepipe 54 to the evaporator 5|, but before being discharged into saidevaporator it passes through a heat interchanger 55 While still undercondenser pressure and then through a refrigerant expander or restricter56. The refrigerant, after having been expanded in the restricter 56,passes through the pipe 51 to the inlet end' of the relatively long,'narrow refrigerant space 5|a of the evaporator 5|. The refrigerant inlet.of the evaporator is placed at the upper end 58 of the arm 58a of theevaporator. The evaporator is in the form of a U and is formed of twosheet metal plates 59 and 50, the plate 60 having corrugations ordimples 60a formed thereon spaced sufdciently frequently so that the twoplates 5S and 60 may be spot-welded together at said dimples to form therefrigerant space 5|a. The refrigerant flows between the plates 59 and60 down the arm 58a, around the curved bottom 6|, and' thence up the arm62. At the top of the arm 62 a semi-cylindrical channel 63 is made inthe plate 59', and this forms the outer casing of the interchanger 55and at the same time' forms the refrigerant outlet of the evaporator 5|to which is connected the pipe 64 leading to the compressor |0. In thisstructure the effective refrigerating area of the evaporator extendsfrom the inlet 58 at the upper portion of an arm 58a and extends atvarious distances under lvarying conditions downthe arm 58 minates atsome point intermediate inlet 58 and outlet 63 of the evaporator.

In this form an ice cube freezing space is provided by placing shelves65 and 66 on lugs 61 and.

68 formed on the plate 59. Since this part of the evaporator is shieldedby the top plate69 and end plates 69a and 69h from the circulating airin the food preserving space 50a of the cabinet, this portion of theevaporator is cold enough to freeze ice cubes within a reasonable time.The end plate 69a. is provided with openings 69o for the reception ofice cube freezing trays 69d.

The restricter or expander 56 is of any suitable construction whichprovides a long orifice through which the refrigerant expands beforebeing delivered to the evaporator. One form which has been foundsatisfactory includes an outer cylindrical shell 10 placed over abolt-like cylindrical member 1I which is provided with a triangularthread 12, this thread forming a long continuous passage for theexpansion of refrigerant. In one method of assembly, the shell 10 isheated to a relatively high temperature, and is placed over the member1| so that it contacts tightly in fixed position on said member 16. Ifdesired a screen 13 is placed within the inner cavity 14 of the boltlikemember 1I and its end contacts with the boltlike member 1| at the point15. The other end of lthe screen 13 is secured at the point 16 to thecylindrical member 1 0. The refrigerant from the condenser passingthrough the pipe 54 enters the restricter or expander at the point 11,passes through the screen 13, and then enters the end 18 of therefrigerant passage formed by the thread 12, finally discharging throughthe radial passage 19 into the outlet end 80 connected to the pipe 51which leads to the inlet of the evaporator. The interior of the shell 10and the exterior of the bolt-like member 1l are preferably chrome-platedand given a smooth nish. In the form shown, the capillary passage formedby the thread 12 is neither adjustable as to length or area.J This formof expander is preferably used in thevnished product after allpreliminary calibrations have been terminated. If this type of expanderis to be used for calibration purposes several of these expanders aremade having different dimensions, so that they may be substituted duringcalibration until one of the proper length and cross-sectional area isconstructed.

If quicker freezing is desired than is provided bythe evaporator shownin Figs. 4 to 6, the modiflcation shown in Fig.7 may be used. In thismodification the refrigerant, after having passed through the heatexchanger 80, corresponding to the exchanger 56, passes through therefrigerant restricter or expande;` 8l corresponding to the restricter56. Thereafter the refrigerant contacts first with the ice freezingmeansby passing through a pipe 82 downwardly and in contact with the bottomof the ice tray shelf 83. The contact is preferably in the form ofsinuous loops 82a, the pipe being attached or soldered to the plate 83.Thereafter the refrigerant passes through the portion 84 of the pipe 82and enters the refrigerant inlet 85, which corresponds to therefrigerant inlet 58 heretofore described. Thereafter the re.

frigerant ows down the arm 86 and continues around thejevaporatorsubstantially in the same manner as'fdescribed with respect to Figs. 4to 6. The pipe 82 is shown as contacting only lwith the tact with thesecond or remaining shelves. The shelves 83 are thermally insulated fromthe outer surface of the evaporator, by being spaced as shown at 88 fromthe outer shell of the evaporator. Small lugs are used for supportingthe shelves, but the lugs are made as small as possible, so as toprovide the least possible thermal contact.

The description heretofore made with respect to the proper design of therefrigerating system and the expander, is not altered by the icefreezing means described. The system and the expander are designed asthough no ice freezing is to be provided, and the system automaticallyincreases its capacity when the ice trays with water are introduced intotheevaporator. When the ice trays are introduced, the back pressure andvhead pressure automatically increase for a short period of time, thusmaterially increasing the capacity of the system temporarily, andthereafter the pressures tend to restore to the normal conditions. Inthe cabinet constructed by me, of substantially 5 cu. ft. internaldimension, ice trays having a total capacity of 4 lbs. of ice wereprovided in an evaporator similarto that shown in Fig. '7 and it wasfound that ice was frozen in about four hours at the 60 F. roomtemperature and in a relatively longer period of time in the 110 room.

The evaporator should have sufficient area to provide sufficient heatexchange with the atmosphere in the food preserving space 50a of thecabinet under the heaviest load conditions. In the preferred form, theevaporator is constructed to provide a long surface contact and therefrigerant is introduced at one end and is removed at the other. Theeffective refrigerating area extends in varying lengths from the intakeof the evaporator according to refrigeration conditions. This area ismore or less clearly indicated by the formation of frost on theevaporator, the point of its termination indicating the place where the7 l plate 83 at the loop 82a, but the pipe may also continue downwardlyafter this contact and conlast substantial traces of liquid refrigeranthave been converted into gas. This effective refrigerating areaincreases as the outside or room temperature increases because of theincreased amount of refrigerant liquid entering the evaporator. Thetemperature. of the refrigerant within the evaporator also increasesWithrise in outside temperature. However, the increase in re'-frigerating area, imposed by the greater quantity of liquid refrigerant,is relatively greater inproportion than the increase in refrigeranttemperature, so that the air cooling effect Within the cabinet isincreased notwithstanding the rise in evaporator temperature.

l The evaporator may be of any shape which permits proper compensationbetween air cooling capacity and heat inltration, such as a straighthollow vertical plate, and ice freezing means may Lbe isolated from themain evaporator, the refrigerant rst passing through the ice freezingmeans, but it is preferred to construct the same in the forms shown anddescribed.

The compressor is started by a hand switch 90 which includes a startingcircuit control and an overload control. This switch is intended to beused only when the system is originally started after installation, andthereafter only when the evaporator is to be defrosted or when thesystem is to be inspected or repaired.

Other forms of refrigerant expanders or restricters may be used. Forexample, an expander may be used in which a pressure responsive flexiblemember or bellows automatically varies the refrigerant passage orpassages, the bellows being connected to a thermostatic bulb placed inthermal contact with the air surrounding the cabinet or in thermalcontact with the condenser, the control being such that when the roomtemperature rises, the expander is opened more to permit a greater flowof refrigerant into the evaporator and thus cause an increase inevaporator temperature and effective refrigerating area substantially inthe same manner and to the same degree of variation as the capillaryrestricter heretofore described. Another type of expander which may beused is one in which a pressure responsiveiiexible member or bellowsautomatically varies the refrigerant passage or passages,

the bellows being connected with a thermostatic bulb placed in thermalcontact with the interior of the cabinet, preferably at a placesuiiciently removed from the evaporator so that it is responsive only tocabinet food preserving compartment temperature rather than evaporatortemperature. In this construction the arrangement is such that with aslight rise in cabinet temperature (but still within food preservingtemperature limits) due to a rise in room temperature the expander isopened more to permit a greater flow of refrigerant into the evaporatorwith a consequent increase in evaporator temperature and effectiverefrigerating area, also substantially in the same manner andsubstantially to the same degree as the capillary restricter heretoforedescribed; Still another type of expander may have pressure responsiveflexible member or members for varying the refrigerant passage orpassages, the pressure responsive member or members being responsive tocondenser and evaporator pressures in such a manner that the expanderautomatically increases the evaporator temperature and effectivecrosssectional area in accordance with arise in condenser pressure (afunction of the room temperature) in an amount sufcient to maintain foodpreserving cabinet temperatures under varying room temperatures. Some ofthese types of expanders or restricters are, of themselves, Well knownin the art; but they have not been used in a cabinet and refrigratingsystems which have been coordinated as herein disclosed.

mately 32 F. to approximately 50 F. which is suitable for preserving theordinary foods used in a household and at the same time it is desired toprovide a relatively small compartment of lower temperature suitable forfreezing water, desserts and the like. These further coordinating stepsare now described.

FURTHER CQORDINATING S'rnrs Fon HOUSEHOLDl RE FRIGERATION WITH IonPomzfcino.v MEANS When applying the principles of this invention to ahousehold refrigerator the relationship of the refrigeration capacity ofthe system, the lieat leakage into the cabinet, and the evaporatorpressures are coordinated with regard to the freezing temperature ofwater so that the ice-I making compartment of the evaporator operates atall times below the freezing temperature of. water; and so that thesystem has sufiicient reserve refrigerating capacity to freeze thewater. The parts are so coordinated that the restricter varies thecapacity of the system throughout the normal room temperature range(60-110) in an amount suillcient to produce the required quantity of iceand to maintain the cabinet Within the food preserving temperature zone.

The cabinet temperature, normally to be maintained, is selectedsufficiently below the highest acceptable food preserving temperature(approximately 50) so that when a heavy unusual refrigeration load isplaced on the system (such as that due to ice making) the cabinettemperature can rise temporarily several degrees and still be below theupper accepted food preserving limit. This permissible rise in cabinettemperature reduces temporarily the refrigeration requirements of thecabinet and makes available a certain portion of the refrigerationcapacity of the system for making ice. The rise in cabinet temperaturealso makes available or releases a certain amount of refrigeration dueto the holdove'r capacity of the cabinet and its food content. Moreover,when any extra refrigeration load is placed on the system, such as whenthe cabinet must be initially cooled, or when food is introduced intothe cabinet, or when Water for ice making is introduced in an evaporatorconstructed as herein disclosed, the refrigeration capacity of thesystem automatically increases a certain amount to meet the increasedload, so that this excess capacity is made available for ice-making inaddition to the gains in refrigeration caused by the rise in cabinettemperature.

These coordinating steps are now more fully described with reference toFigs. 10 and l1. Fig. 10 has a chart substantially similar to Chart A ofFig. l, with additional information placed thereon illustrating some ofthese coordinating steps introduced by these ice-making requirements. InFig. 11 Chart F corresponds with Chart A of Fig. 1 and showscharacteristics of a system of proper capacity for the particularcabinet used. Chart C, Fig. 11, is representative of a refrigeratingsystem which has too great a capacity to use to the full extent all ofthe advantages of this invention, when such a system is used with acabinet of the heat leak under consideration, Chart H is representativeof a refrigerating system of a capacity to small to provide ice-makingtemperatures in the evaporator when used with a cabinet of the heat leakunder consideration.

Fig. 10 shows a refrgerating system substantially of the same characteras that shown in Fig. l and in Chart F of Fig. l1, but there has beensuperimposed on the room temperature lines of Fig. 10 two lines, llpandIll which represent respectively constant cabinet temperatures of 32 and50 and are plotted from results obtained by multiplying the heat leakcoeincient (3.4) times the heat differential between the cabinet androom temperatures. The space between these two lines represents the foodpreserving temperature zone in which the cabinet may be satsfactorilymaintained. The refrigerant expander may be calibrated to maintain thecabinet temperature anywhere within this zone, and therefore .maymaintain'cabinet temperatures corresponding to lines,'C", |12 or |13 orany other line which may be drawn within the zone, so that some of theadvantages of this invention may be attained even if the cabinettemperature varies slightly but still lies within the acceptable foodpreserving temperature zone. The food preserving zone indicated is theone which is generally accepted for domestic household refrigerators. Itis to be understood that different zones may be established whereconditions are different from those in a domestic refrigerator, andwhere this invention is applied to cabinets in which other articles arerefrigerated which have special refrigeration requirements, then thepermissible zone of cabinet temperature may be adjusted to theparticular requirements of the articles being cooled.

The line C" lies very nearthe lower limit line |10, and corresponds toline C, C of Figs. 1 and 9. The cabinet temperature of a refrigeratoroperating in accordance with line C can rise considerably before itpasses the upper limit of the food preserving zone. The ice-makingcapacity of the system is preferably limited to an amount such that,while it may temporarily cause a slight risevin cabinet temperature,still it does not cause the-cabinet temperature to rise above A systemof refrigerating capacity is used such that the point (the normaloperation evaporator pressure at the highest room temperature) is asuicient distance below line |20 (which corresponds to the freezingtemperature of water) to provide a vcold enough temperature and reserverefrigerating capacity for the ice-making capacity desired. The point|15 (204 B t. u.s) is the vertical reading from point |16 (50 cabinettemperature in 110 room) while the point |11 (251.6 B. t. u.s) is thevertical reading of point |55 (the normal cabinet temperature in 110room). and |11 (bracket |80) represents the residual refrigeratingcapacity available for ice-making when the cabinet temperature rises tothe highest permissible limit (50 F.). The holdover capacity of thecabinet and its contents also becomes available for ice-making since itreleases refrigeration in warming from 36 (normal operation) to 50 byabsorbing heat, thus making a further amount-of refrigeration availablefor ice- `making. The heat thus absorbed is indicated, for

convenience, as bracket X in Fig. 10. In addition, the capacity of thesystem automatically and inherently increases slightly when Water to befrozen is placed in the evaporator. Instead of operating at point 55,the system operates at slightly increased capacity indicated by thepoint |18. Its vertical reading |19 indicates the total B. t. 1.1.sproduced by the system under this abnormal load, of which the ice-makingcapacity of the system is represented by brackets X and |8|. The heatexchange capacity between the evaporator and the ice trays issovproportioned that the ice trays cannot transfer heat at a rate fasterthan is represented by the brackets X and |8| for any extensive periodof time. When the evaporator is so proportioned or constructed, thecabinet temperature will not rise above the highest permissible limit(50 F.) while ice is being produced. Since substantially the same ormore favorable conditions prevail throughout the entire room temperaturerange, this provision for ice-making is automatically correct for allother room temperatures. With the particular cabinet herein described,and with an evaporator substantially as shown in Fig. 7, with twoshelves refrigerated by pipe 82a, and two ice trays totalling 4 lbs. ofwater were frozen in ve hours in a 110 room. From the aboveit will beseen that the system is provided with means for maintaining l Thedistance between points |15 tures in the ice-making space throughout thenormal room temperature range notwithstanding the continuous operationof the compressor.

Chart F, Fig. 1l shows a system of desirable capacity for ice-makingfacilities in'the cabinet under consideration. This chart shows the samesystem'heretofore described with respect to Figs. 1, 9 and 10, the roomtemperature lines and the cabinet line C of Chart F showing the samevalues as the corresponding lines in Figs. 1', 9 and 10, but is shown ona reduced scale so that the system may be shown in its relation tosystems having less desirable refrigeration capacities. Chart Fconsidered with Fig. l0, yillustrates the proper coordination ofthecapacity of a refrigerating system with a household cabinet equipped formaking ice cubes.

Chart G is representative of a system having more refrigerating capacitythan is required for the particular cabinet under consideration. Thesystem is capable of producing more than twice the number of B. t. u.sper hour in a F. room at the same back pressure than is produced by thesystem corresponding to Chart F. The system of Chart G when coordinatedwith the 'particular cabinet operates at unnecessarily low evaporatorrefrigerant temperatures, the theo- .retical vapor temperature in theevaporator actually being below 0 F. in the maximum normal roomtemperature of 110 F. Because of this,l such a system takes only partialadvantage of the features of this invention, since it operates atundesirably low efficiencies, and, unless extremely low temperatures orextremely fast freezingcapacities are desired, a system of vlesscapacity is more advantageous. -The line C shows the back pressures atwhich such a system must operate in order to maintain cabinettemperatures equivalent to those of lines C, C' and C in the particularcabinet being investigated.

Chart H is representative of a system which .does not have suicientcapacity to freeze ice.

or maintain food preserving cabinet temperatures at the higher roomtemperatures. The

line C" shows the back pressures necessary in is not below 32 F., and isincapable of freezing l ice at these higher room temperatures.Furthermore, the points |92 and |93 occur above the line |2|(corresponding to evaporator vapor temperature of 50 F.) and thereforethe system is incapable of producing low enough temperatures in theevaporator to maintain a food preserving temperature in the cabinet. Itis therefore undesirable to utilize a system of the capacity shown inChart H where ice freezing is necessary at the higher room temperatures.

While I have indicated that a system having the characteristics shown inFig. 10 and Chart F utilizes to the greatest extent the features andadvantages of my invention when used in a household refrigeratorequipped for ice-making, it is to be understood that many systems havinggreater or less relative refrigerating capacities may be used in thepractice of my invention, v

and that such systems embody many features of my invention and attainits many advantages 1. A refrigerating apparatus consisting of a`household refrigerator' cabinet having a food preserving space and anice-making space, a com- .pressor-condenser-evaporator refrigeratorsystem 4 assembled with said cabinet, said compressor operatingcontinuously at constant speed and circulating refrigerant continuouslythroughout the system andthroughout the normal room temperature rangewithout stopping for cabinet temperature adjustments, a fixed passagerestricter of proper cross-sectional area and length for varying thecapacity of the system throughout the normal room temperature range inan amount sulcientto produce the required quantity of -ice andtomaintain the cabinet within the food preserving temperature zone, saidsystem being of sufficient capacity 'so that the effective vaportemperature in the evaporator is below 32 F. and being of sufficientlysmall capacity that the effective Vapor temperature in the evaporator is`above 0 F. while the system operates in the maxlmumnormal roomtemperature.

2. A refrigerating apparatus consisting of a household refrigeratorcabinet having a food preserving space and an ice-making space, acompressor-condenser-evaporator refrigerator system assembled with saidcabinet, said compressor operating continuously at constant speed andcirculating refrigerant continuously throughout the system andthroughout the normal room temperature range without stopping forcabinet temperature adjustments, said evaporator having a relativelylong refrigerant passage between its inlet and outlet in thermal contactwith an ice-making space and means shielding said icemaking space fromthe food preserving space of the cabinet, and an elongated orificebetween said condenser and the inlet of said evaporator having a lengthand cross-sectional areancoordinated with the heat leak`into' thecabinet un-` der varying room temperatures so that the evaporatormaintains the cabinet temperature within food preserving limits and theice-making space below 32 F, notwithstanding the continuous operation ofthe compressor and the variations in room temperature.

3. A refrigerating apparatus consisting of adomestic refrigeratorcabinet having a food preserving space and a freezing space shieldedfrom said food preserving space, a compressor-condenser-evaporatorrefrigerator system assembled and transportable with said cabinetias aunit, said system being of a capacity not substantially in excess of themaximum normal refrigeration requirements of said cabinet undercontinuous compression operation. said compressor operating continuouslyat constant speed and circulating refrigerant continuously throughoutthe system during the entire refrigeration requirements of the cabinetwithout stopping for cabinet temperature adjustments, an evaporator insaid cabinet having a relatively long refrigerant passage between itsinlet and outlet in thermal contact -with said fr'eezing space and saidfood preserving space of the cabinet. and a refrigerant expander betweensaid condenser and the inlet of said evaporator having a fixed lengthand crosssection of a size which varies the cooling capacity of saidevaporator in an amount sufficient to lmaintain the cabinet temperaturewithin food l v domestic refrigerator cabinethaving a food preservingspace, a compressor-condenser-evaporator refrigerator system assembledand transportable with said cabinet as aunit, vsaid system being of acapacity not substantially in excess of the maximum normal refrigerationrequirements of said cabinet under continuous compression operation,continuously at constant speed and circulating refrigerant continuouslythroughout the system said evaporator having a length andcross-sectional area coordinated with the heat leak into thecabinet'under varying room temperatures so that it varies the evaporatorcooling capacity said compressor operating .during the entirerefrigeration requirements of the cabinet without stopping for cabinettem-A in an amount suflicient to maintain the cabinet food preservingspace temperature within food preserving limits notwithstanding thecontinuous operation of the compressor and the variations in roomtemperature.

5. A refrigerating apparatus consisting of a household refrigeratorcabinet having a food preserving space and an ice-making space, acompressor condenser evaporator refrigerator system assembled with saidcabinet, said compresser operating continuously at constant speed andcirculating refrigerant continuously throughout the system andthroughout the normal room temperature range without stopping forcabinet temperature adjustments, and an elongated orifice of a lengthand cross-sectional area sufficient for varying the capacity of thesystem throughout the normal room temperature range in an amountsufficient to produce the required quantity of ice and to maintain thecabinet within the food preserving temperature zone.

6. A refrigerating apparatus consisting of a household refrigeratorcabinet having a food preserving space andan ice-making space, acompressor condenser evaporator refrigerator system assembledwitnsaidcabinet, said compressor operating continuously at constant speed .l

and circulating refrigerant continuously throughout the system and,throughout the normal room temperature range without stopping forcabinet temperature adjustments, an elongated orifice of a length Aandcross-sectional area sufficient forl `varying the capacity of the4preserving space and an ice-making space, a

compressor condenser evaporator refrigerator system assembled with saidcabinet, said cornpressor operating continuouslyy at constant speed andcirculating refrigerant continuously throughout the system andthroughout the normal room temperature range, an elongated orifice -of alength and cross-sectional area sumcient for varying the capacity of thesystem throughout the normal room temperature range in an amountsuicient to produce the required quantity of ice and to maintain thecabinet within the food preserving temperature zone, said system beingnot more than twice the refrigeration capacity required to maintain thecabinet within the food preserving temperature zone and to produce therequired quantity of ice in the maximum room temperature.

8. A refrigerating apparatus consisting of a household refrigeratorcabinet having a food preserving space and an ice-making space, acompressor condenser evaporator refrigerator `system assembled with saidcabinet, lsaid compressor operating continuously at constant speed andcirculating refrigerant continuously throughout the system andthroughout the normal temperature range without stopping for cabinet,temperature adjustments, 'an elongated orice of a length andcross-sectional area sufficient for varying the capacity of the systemthroughout the normal room temperature range in an amount suiiicient toproduce the 'required quantity of ice and to maintain the cabinet withinthe food preserving temperature zone,.said system being of sumcientcapacityV so that the eiective vapor temperature in the evaporator isbelow 32 F. while the system operates in the maximum normal roomtemperature, and said system being not more thanv twice therefrigeration capacity required to maintain the cabinet within the foodpreserving temperature zone and to produce the required quantity of icein the maximum room temperature,

9. A refrigerating apparatus consisting of a household refrigeratorcabinet having a. food preserving space and an ice-making space, acompressor condenser evaporator refrigerator system assembled with said'cabinet, said com- .cabinet having a food preserving zone, arefrigerating system therefor of a capacity not substantially in excessof the maximum normal refrigeration requirements of said cabinet, saidsystem comprising a compressor, a condenser, a xed restriction and anevaporator provided with a freezing zone, all having passages and beingconnected in series to form a closed refrigerant circuit, the relativeproportion of the parts of the system being such that the rate of heatabsorption at the evaporator is automatically varied to maintain thetemperature of said food preserving zone above 32 F. and within foodpreserving temperatures and the freezing zone below 32v F. while thecompressor runs continuously at constant speed and the size of everypassage in the system is maintained unchanged.

ANDREW A. KUCHER.

